libct/cg/fs: fix setting rt_period vs rt_runtime #5992

Job	Run time
cross-i386	1m 25s
cross-i386 (runc_nodmz)	1m 37s
test (ubuntu-20.04, 1.20.x, rootless, -race)	6m 36s
test (ubuntu-20.04, 1.20.x, rootless)	6m 10s
test (ubuntu-20.04, 1.20.x, -race)	7m 4s
test (ubuntu-20.04, 1.20.x)	6m 23s
test (ubuntu-20.04, 1.21.x, rootless, -race)	6m 49s
test (ubuntu-20.04, 1.21.x, rootless)	5m 59s
test (ubuntu-20.04, 1.21.x, -race)	7m 3s
test (ubuntu-20.04, 1.21.x)	6m 9s
test (ubuntu-20.04, 1.21.x, criu-dev)	7m 9s
test (ubuntu-22.04, 1.20.x, rootless, -race)	10m 26s
test (ubuntu-22.04, 1.20.x, rootless)	10m 6s
test (ubuntu-22.04, 1.20.x, -race)	8m 29s
test (ubuntu-22.04, 1.20.x)	7m 49s
test (ubuntu-22.04, 1.21.x, rootless, -race)	10m 2s
test (ubuntu-22.04, 1.21.x, rootless)	10m 15s
test (ubuntu-22.04, 1.21.x, -race)	8m 35s
test (ubuntu-22.04, 1.21.x)	7m 54s
test (ubuntu-22.04, 1.21.x, runc_nodmz)	7m 44s
test (ubuntu-22.04, 1.21.x, criu-dev)	8m 34s
test (actuated-arm64-6cpu-8gb, 1.21.x, rootless)	11m 2s
test (actuated-arm64-6cpu-8gb, 1.21.x)	7m 4s
	2h 50m 24s

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